Webbing and belting means for use in seat belts

ABSTRACT

Weight belt restraining structure having a webbing with a multiple-step give. The webbing belts and the like having a multiple-step give. The webbing has a first warp of yarn of medium strength high tensility and has a second and third warp of yarn of low strength low tensility, medium strength medium tensility, on high strength low tensility as compared with the strength and tensility of the first warp. The weft is yarn of medium strength and high tensility. All of the warp yarns are sufficiently strong so they are not broken until the initial load applied to the webbing reaches a predetermined value between 2001,000 kg, and the warp yarns also have sufficient strength not to elongate in proportion to an increase in load. Above the predetermined load value, the second and third warp yarns are gradually and repeatedly broken while the shape of the web is maintained by the first warp yarn and the weft until the tensility reaches a predetermined value after the initial load reaches such a value, after which the webbing elongates without an increase in the load applied thereto. The webbing does not return to its initial state with a violent recoil after removal of the load, due to the action of the first and second warps, thereby giving the webbing a multiple-step give with a loaddeflection curve substantially in the form of a parallelogram.

United States Patent [19] Sen et al.

[111' 3,820,843 [451 June 28, 1974 WEBBING AND BELTING MEANS FOR USE IN SEAT BELTS [75] Inventors: Kiyokazu Seo; Yoshihiro Hayashi,

both of Toyota; Tunekichi Hoshino; Fumiyoshi Masuda, both of Joetsu, all of Japan [73] Assignees: Toyota Jidosha Kogyo Kabushiki Kaisha, Toyota-shi, Aichi-ken;

Kabushiki Kaisha Tokai Rika Denki Seisakusho, Aichi-ken; Hoshino Kogyo Kabushiki Kaisha, Niigata-ken, all of, Japan 221 Filed: Dec.18, 1972 211 Appl. No.: 315,826

Related US. Application Data [62] Division of Ser. No. 236,749, March 21, 1972, Pat.

[52] US. Cl. 297/389 [51] Int. Cl A62p 35/00 [58] Field of Search 297/386, 384, 385, 387, 297/388, 389, 390; 280/150 SB [56] References Cited UNITED STATES PATENTS 2,352,036 6/1944 Tauty 297/386 X 2,475,588 7/1949 Bierman 297/386 X I 2,613,865 10/1952 Rose 297/386 3,302,973 2/1967 Ravau 297/386 3,414,322 12/1968 Linderoth 297/389 3,424,495 1/1969 Cherup 297/386 AnA 3,550,957 12/1970 Radke ..297/386 Primary Exaniiner.lames T. McCall Attorney, Agent, or FirmWenderoth, Lind & Ponack 5 7] ABSTRACT Weight belt restraining structure having a webbing with a multiple-step give. The webbing belts and the like having a multiple-step give. The webbing has a first warp of yarn of medium strength high tensility and has a second and third warp of yarn of low strength low tensility, medium strength medium tensility, on high strength low tensility as compared with the strength and tensility of the first warp. The weft is yarn of medium strength and high tensility. All of the warp yarns are sufficiently strong so they are not broken until the initial load applied to the webbing reaches a predetermined value between 2001 ,000 kg, and the warp yarns also have sufficient strength not to elongate in proportion to an increase in load. Above the predetermined load value, the second and third warp yarns are gradually and repeatedly broken while the shape of the web is maintained by the first warp yarn and the weft until the tensility reaches a predetermined value after the initial load reaches such a value, after which the webbing elongates without an increase in the load applied thereto. The webbing does not return to its initial state with a violent recoil after removal of the load, due to the action of the first and second warps, thereby giving the webbing a multiplestep give with a load-deflection curve substantially in the form of a parallelogram.

8 Claims, 15 Drawing Figures AnA PATENTEDJUN28 I974 sum 5 or 6 Q9 oi om oN 0 0 9 Om ow ox. 0% 0m ow om ON 2.

3 8* on 3 2 c2 8 8 E 8 n 3 on mwOE Auwmv wE WEBBING AND BELTING MEANS FOR USE IN SEAT BELTS This application is a division of US. Pat. Ser. No. 236,749, filed Mar. 21, 1972 now US. Pat. No. 3,756,288.

This invention relates to webbing and belting means for use in seat belts for easing mechanical shocks applicable to drivers of automobiles and crew of airplanes and the like in the case of collisions of such vehicles and preventing said drivers and crew from secondary collisions against structures inside the vehicles, and also for use in parachute belts, life belts for workers at high altitudes, and the like.

Heretofore, safety belts of this kind were constructed of webbing comprising two kinds of warp each having different elasticity as disclosed, for example, in the specification of US. Pat. No. 3,464,459. However, the belt webbing of said US. Patent is not so constructed as will induce a correlative function between the two kinds of war p, i.e., the core warp and the other warp which function independently of each other. When the correlative function is lacking between the two kinds of warp, there is no multiplicative energy absorption oetween said two kinds of warp, and the functions of safety belt as described hereinbefore can scarcely be expected from such webbing.

Furthermore, the specification of US. Pat. No. 3,148,710 discloses a device wherein a binding medium for binding two kinds of warp is interposed therebetween thereby enabling to obtain a correlative function between the two kinds of warp each having different elasticity when an instantaneous impact is applied thereto. However, such construction will increase the thickness of the belt involving the defects of necessitating a large-sized retractor particularly in the case of a type wherein the belt when not used is retracted into a retractor, and depriving the belt of flexibility when said belt is fitted.

A first object of this invention is to obtain webbing having the multiple-step give wherein the warp resists a predetermined initial load, a subsequent increase in load being disposed of by elongation and intermittent repetition of breakage of particular warp thereby preventing an increase in load applicable to the belt, violent recoil after removal of the load being prevented by the resistance of the broken warp, and also to obtain belting means making use of said webbing.

A second object of this invention is to provide webbing having a characteristic of absorbing a predetermined increase in load under spontaneous impact elongation and intermittent repetition of breakage of said particular warp comprising more than two kinds of yarn each having different elasticity and strength, said intermittent repetition of breakage of the particular warp, being accomplished by a correlative function between a first texture comprising main warp and weft and a second texture comprising other warp and said weft without the help of the binding medium.

A third object of this invention is to reduce the production cost by simplifying the texture and to obtain belt webbing easily retractable into a small-sized retractor by reducing the thickness of said webbing.

These and other objects are accomplished by proper combinations of warp yarns to be used and the texture comprising warp and weft, preferred embodiments of which are shown by way of example in the accompanying drawing and herein described in detail. Of the drawings:

FIG. 1 is a longitudinally sectional side view on a magnified scale in part showing the webbing of this invention;

FIG. 2 is a perspective on a magnified scale and broken off in part showing the texture of webbing of this invention;

FIG. 3 is a descriptive plan on a magnified scale showing the texture of the webbing of this invention;

FIG. 4 is a graph showing curves indicating the relation between the load and tensility of a seat belt in which the webbing of this invention is used;

FIG. 5 is a graph showing curves indicating the relation between the strength and tensility of the yarn for use in the webbing of this invention;

FIG. 6 is a graph showing curves indicating the relation between the load and tensility of a seat belt in which is used webbing of another embodiment of this invention;

FIG. 7(a) is a graph showing curves indicating the relation between the load and tensility when the webbing of this invention is used for a waist belt;

FIG. 7(b) is a graph showing curves indicating the relation between the load and tensility when the webbing of this invention is used for a shoulder belt;

FIG. 8(a) is a graph showing curves indicating the relation between the load and tensility of the known webbing for a waist belt;

FIG. 8(b) is a graph showing curves indicating the load and tensility of the known webbing fora shoulder belt;

FIG. 9 is an elevation of a tripple seat belt so called three-points seat belt comprising in combination the waist belt webbing having the load-tensility property shown in FIG. 7(a) and the shoulder belt webbing having the load-tensility property shown in FIG. 7(b);

FIG. 10 is an elevation of a tripple seat belt comprising in combination the known waist belt webbing having the load-tensility property shown in FIG. 8(a) and the known shoulder belt webbing having the loadtensility property shown in FIG. 8(b);

FIG. 11 is a graph showing curves indicating the relation between gravity and time duration arising on the floor of a vehicle in an impact test;

FIG. 12 is a graph showing curves indicating the relation between forward and backward gravity and time duration in connection with the head of a dummy in an impact test;

FIG. 13 is a'graph showing curves indicating the relation between the load arising at the anchorage 7 the shoulder belt and the time duration in an impact test;

FIGS. 14 and I5 are elevations showing still another embodiment of the invention.

Referring now to FIGS. 1 to 3, the numerals ll, 12, I

13 and I4 designate warp respectively, 15 designating weft, each comprising yarn as described hereinunder.

two threads of weft 15, thereby constituting a first texture consisting of so-called 2 up 2 down twill.

Furthermore, warp 12, 13, each comprising a plurality of threads arranged in parallel, run across weft 15 up and down alternately, thereby constituting a second texture which is a plain web. Moreover, warp 14 runs across weft 15 up and down alternately between each adjacent warp 11, thereby constituting part of the second texture which is a plain web.

FIG. 3 shows the construction of the texture described hereinbefore. In this construction chart warp runs longitudinally, weft running transversely, white squares showing where warp runs over weft, black squares showing where warp runs under weft.

In the texture above mentioned, suitable yarn for warp 12 is polyamide fiber yarn of which tensility has been increased by a boiling process in hot water at temperatures 95 100 C for 25-30 minutes, the tensility being increased by approximately 10 percent by the said boiling process. The same yarn as said processed warp 11 may be used for the second texture in addition to warp 12, 13 and 14, if necessary.

With regard to warp 12, two, three, four or-five threads instead of a single thread may be passed in combination in some section of the web.

Each embodiment of webbing shown in FIGS. 1 to 3 is described hereinunder.

EMBODIMENT NO. 1

An automobile seat belt webbing having a breadth of 50mm was woven into texture as shown in FIG. 3 making use of warp ll, 12, 13, I4 and weft 15 of the description as set forth hereinunder.

Warp 11: 188 threads of Type 6 nylon (Teijin Nylon T500, brand of polyamide synthetic fiber of Teijin K.K., Japanlof medium strength high tensility (relation between both properties as per FIG. of 840/96 l/2S I40 T/m Warp 12: 100 threads of Teijin Tetoron R120 (brand of polyester synthetic fiber of Teijin K.K., Japan) of low strength low tensility (relation between both properties as per FIG. 5) of 250/24 l/2S 75 T/m Warp I3: threads of Teijin Tetoron P500 (brand of polyester synthetic fiber of TeijinK.K., Japan) of high strength lo w tensility of 1000/250 l/lS I00 T/m Warp l4: l0 threads of Teijin Tetoron R620 (brand of polyester synthetic fiber of Teijin K.K., Japan) of medium strength medium tensility (relation between both properties as per FIG. 5) of 1000/250 l/lS 100 T/m Weft I8 pick/inch of Type 6 nylon (Teijin Nylon T500, brand of polyamide synthetic fiber of Teijin K.K., Japan) of medium strength high tensility (relation between both properties as per FIG. 5) of 840/96 l/ZS I00 T/m By giving tensile stress to the webbing above mentioned, the relation between the load applied to said webbing and the tensility thereof and the resilience after removal of said load were tested, and the result was as per the graph shown in FIG. 4, of which the vertical axis indicates an increase in load upwardly, the transverse axis indicating elongation of the belt in the right direction.

As is clear from this graph, the belt, under load not greater than 400 kg, was rectilineally elongated by 7 8 percent, the load being absorbed by the belt from Point A onward, the elongation reaching approximately 25 percent at Point B. The principle of the function of warp ll, l2, 13, 14 and weft 15 between Points A and B is presumably as described hereinunder.

At Point A warp 12 of low strength low tensility is first broken, thereafter warp l3, 14 except weft 11 are broken according as the load exceeds the strength and tensility of said warp. After the load reaches Point A primary breakage arises on warp 12, l3, l4 simultaneously and/or successively. If the load is further increased, the first texture including warp 11 which was in loose correlation with the second texture including warp 12, 13, 14 is brought into closer correlation with the latter.

In other words, weft 15 of the first texture which was hitherto in loose engagement with warp of the second texture gives strong pressure support to warp already broken or not yet broken as a result of elongation of warp 11 which has absorbed the load and/or tension of said warp 11 due to direct application of the load thereto through temporary breakage of said other warp, stronger correlation being thus brought between the first texture and the second texture. Consequently, the load is again applied to the warp which were already subjected to the primary breakage through the medium of the first texture, thereby causing a secondary and a tertiary breakage of warp, one after another, with the result that an increase in load applicable to the entire webbing is absorbed effectively.

Though warp 12, 13, 14 are gradually and repeatingly broken, warp 11 of the first texture is free from breakage, the webbing as a whole being subjected to plastic deformation as shown by the curve A B in FIG. 4 thereby absorbing energy.

The value of the initial load at Point A can be determined by selecting the strength, tensility and number of the component threads of warp 12, 13, 14 and particularly l2.

If tensility exceeds 25 percent, the load increases, the

belt being elongated. At Point C where the load reaches 1,130 kg, the tensility exceeds 40 percent, the belt slightly shrinking to Point D with removal of the load. However, since a considerable number of warp have already been broken, the shrinkage is minimizedby the resistance between threads of warp thereby preventing the risk of the human body being harmed by a violent resilient force.

Moreover, by adjusting the number of warp per unit length and the number of weft per unit length, the substantially horizontal portion between A and B of the curve in FIG. 4, that is, the length of the plateau por tion, can be adjusted. Furthermore, it is also practicable to produce a belt wherein the portion between B and C where said plateau terminates and the curve rises upwardly again is maintained horizontally just as the portion between B and E, said B C portion being adapted to be restored to the E D portion after removal of the load.

In the embodiment described hereinbefore warp 11 and weft 15 of the first texture were woven into twilled web. However, the same characteristics can be expected from webbing of plain weave instead of twill and also from webbing wherein the second texture comprising warp 12, 13, I4 is woven into twill web same as the first texture.

Furthermore, webbing for use in safety belts and particularly for shoulder belts can be obtained by selecting the predetermined value of the initial breakage of warp within the scope of 200 800 kg, webbing being adapted to have greater tensility as compared with the increase in load until the tensility reaches 20 30 percent after said predetermined value.

As shown in FIG 6, peak load can be determined prior to the determined value of the initial load and higher than said load by increasing the component number of warp 12, l3, l4 constituting the second texture than in the case of Embodiment No. l as seen in Embodiment No. 2 which is described hereinafter, and by giving comparatively great tension to warp ll of the first texture. Such peak load serves to ease gravity applied to the human head byimpact.

As described hereinbefore, if the warp 11 is woven at higher tension, the broken warp shall be pressedly suspended by the first texture simultaneously with the initial breakage, thereby said warp shall not slip in the first and second texture and shall serve its function. In other words, since the broken warp is pressure supported by the first texture said warp is capable of working in resistance to the subsequent load promptly after the breakage.

EMBODIMENT NO. 2

Webbing having the identical breadth with Embodivment No. l was produced in the identical texture with said embodiment making use of warp ll, 12, 13, 14 and weft 15 which are identical with said embodiment only excepting the number of threads. However, the webbing was produced by applying greater tensile strength (300 350 g/thread) to warp 11 than that of Embodiment No. l (150 200 g/thread).

Warp 11: 188 threads Warp 12: 180 threads Warp l3: 18 threads Warp l4: 18 threads Weft l5: l8 pick/inch By applying tensile strength to the above-mentioned webbing. the relation between the load and tensility as well as the resilience as the time of removal of said load was tested, the result of which was as shown in FIG. 6. The webbing has proved to have excellent properties for seat belts and particularly for shoulder belts as described hereinbefore.

l is used in the shoulder belt and webbing of another kind of this invention is used in the waist belt.

' EMBODIMENT NO. 3

Teijin Tetoron R I20 Warp l l: 160 threads Warp l2: Teijin Tetoron P500 40 do. Weft l5: Teijin Tetoron R120 18 pick/inch A triple seat belt A as shown in FIG. 9 was constructed with webbing of Embodiment No. 3 used as webbing for the waist-belt 21 and with webbing having the load-tensility property as shown in FIG. 7 (b) used as webbing for the shoulder belt 22. Referring to FIG. 9, the numeral 23 designates a buckle, AnA, AnA and AIM." designating anchorages.

On the other hand, a triple seat belt B as shown in FIG. 10 was constructed making use of known webbing as waist belt webbing 24 having the properties shown in FIG. 8 (b) and shoulder belt webbing 25 (having the properties as shown in FIG. 8 (b) In said figure, the

Furthermore, though warp 11 and weft l5 constitut- In addition thereto, the webbing of this embodiment can be used for seat belts and particularly for shoulder belts by setting the predetermined value of the initial load within the scope of 200 800 kg, the warp being adapted to have greater tensility as compared with an increase in load until the tensility reaches 20 30 percent after said predetermined value.

The seat belt in which the webbing of this invention is used in the shoulder and/or waist belt thereof has a distinguished energy absorbing effect.

Hereinunder is described still another embodiment of a triple seat belt wherein webbing of Embodiment No.

numeral 26 designates buckles, AnB, AnB' and AnB" designating anchorages. I

An impact test was conducted by causing an automobile (Carora 1970 model of Toyota AutomobileManufacturing Co., Ltd., .lapanlequipped with saidtriple seat belts A and B respectively to collide against a stationary barrier with an initialcolliding speed of 47 km/h. The gravity which acted on the floor of the automobile was as shown in FIG. 11.

The gravity which acted in the forward'and'backward direction on the head of the dummy restrained by the belt A was as indicated by the curve shown in solid line in FIG. 12, the gravity which acted in the forward and backward direction on the head of the dummy restrained by the belt B being asindicated by the curve shown in thedotted line in said figure. Moreover, the load curves indicating the load applied to anchorages AM and AnB (see FIGS. 9 and 10) of the belts A and B were as shown by the solid line and the broken line respectively in FIG. 13. The maximum loads appeared at said anchorages Am! and AnB of the belts A and B were 678 kg and 868 kg respectively, the loads applied to the anchorage AnA on the side of the center of the car of the shoulder belt of the belt A, the anchorage AnA" on. the opposite side, the anchorage AnB on the side of the center of the car of the belt B, and the anchorage AnB on the opposite side were as designated in the table shown herei nuncler.

AnA' AnA" 981 kg 664 kg AnB Ann" 882 kg 534 kg The test described hereinbefore disclosed that the webbing of this invention had a distinguished effect in energy absorption.

The webbing for the shoulder belt of the said triple seat belt is preferably adapted to have greater tensility as compared with an increase in load until said tensility reaches 20 30 percent after a predetermined value of the initial load, said predetermined value being restricted within the scope of 200 800 kg as in the case of Embodiments No. 1 and No. 2.

The webbing for the waist belt to be combined with theshoulder belt of such triple seat belt is preferably adapted to have greater tensility as compared with an increase in load until the tensility reaches percent after a predetermined value of the initial load, said predetermined value being set within the scope of 500-1,100 kg.

Furthermore, the webbing of Embodiment No. 2 was trially used for the shoulder belt of the triple seat belt with as satisfactory results as those of the abovementioned test.

The seat belt shown in FIG. 9 is an embodiment of the triple seat belt. It goes without mentioning, how- 2. A seat belt as defined in claim 1 wherein the waist belt comprises first warp consisting of yarn of medium strength high tensility and at .least second and third warp, said second and third warp being selected from yarn of low strength low tensility, medium strength medium tensility, high strength low tensility respectively as compared with the strength and tensility of said first warp, said first warp constituting a first texture together with weft consisting of yarn of medium strength high tensility, said second and third warp constituting a second texture together with said weft,'all said warp being adapted not to break until the initial load applied to the webbing reaches a predetermined value set between 500 1,100 kg, said warp also having comparatively great strength not to elongate in proportion to an increase in load, second and third warp being broken ever, that the use of this embodiment enables one to obtain the same satisfactory results if applied to the full-harness type belt and the inverted Y type belt as shown in FIGS. 14 and 15.

ln FIGS. 14 and 15, the waist belt webbing 27,29 is the webbing shown in Embodiment No. 3,'the shoulder belt webbing 28, being the webbing shown in Embodiment No. l or No. 2, thereby constituting a seat belt C, D. in FIGS. 14 and 15, AnC, AnC', AnC" AnD, AnD' and AMD" being anchorages respectively.

As described hereinbefore, this invention enables to obtain webbing having the multiple-step give from woven textures, such as plain web, twill web and the like, said textures though simple in construction being adapted to comprise more than two kinds of warp of each different tensility and thickness which are brought into correlation when violent tension is applied thereto, thereby enabling to obtain satisfactory results.

What we claim is:

l. A seat belt comprising a shoulder belt and a waist belt, 'said shoulder belt comprising at least in part first warp consisting of yarn of medium strength high tensility and'webbing including at least second and third warp, said second and third warp being selected from yarn of low strength low tensility. medium strength medium tensility, high strength low tensility as compared with the strength and tensility of said first warp, said first warp constituting a first texture together with weft consisting of yarn of medium strength and high tensility, said second and third warp constituting a second texture together with said weft, all said warp being adapted not to break until the initial load applied to the webbing reaches a predetermined value between 200 800 kg, said warp also. having comparatively great strength not to elongate in proportion to an increase .in load, second and third warp being gradually and repeatedly broken sustained by the first texture until the tensility attains 2O 30 percent after the initial load reached the predetermined value thereby enabling the webbing to elongate without increasing the load applied thereto, said webbing being a multiple-step give member having a load-flection curve which is substantially a parallelogram wherein restoration by great resilience is prevented by the correlative action between the first and second textures after removal of the load, said waist belt comprising webbing of less tensility as compared with said shoulder belt.

gradually and repeatedly sustained by the first texture until the tensility attains 10 20 percent after the initial load reached the predetermined value, thereby enabling the webbing to elongate without increasing the load applied thereto, said webbing constituting a multiple-step give member wherein the load-flection curve substantially forming a parallelogram and restoration with violent resilience is prevented by a correlative ac tion between the first and second textures after removal of the load.

3. A seat belt comprising a shoulder belt and a waist belt wherein said belt includes at least in part first warp consisting of yarn of medium strength high tensility and at least second and third warp, said second and third warp being selected from 'yarn of low strength low tensility, medium strength medium tensility, high strength low tensility as compared with'the strength and tensility of said first warp, said first warp constituting a first texture together with weft consisting of yarn of medium strength high tensility, said second and third warp constituting a second texture together with said weft, the volume of third warp and the tension of first warp being comparatively increased, a peak load higher than said predetermined value being adapted to work transitionally upon the webbing prior to'the initial load reaching the predetermined value set between 200 800 kg thereby causing said warp to break, said warp being not broken until the load applied to the webbing reaches the value of said peak load, said warp also having comparatively great strength not to elongate in proportion to an increase in the load, second and third warp being broken gradually and repeatedly by a load substantially identical with the value of said predeter: mined load sustained by the first texture until the tensility attains 2O 30 percent after the initial load reached said predetermined value thereby enabling the webbing to elongate without increasing the load applied thereto, said webbing having multiple-step give with the loadflection curve formed substantially in the shape of a parallelogram wherein restoration with violent resilience of said webbing is prevented by a correlative action between the first and second textures after re moval of the load therefrom said waist belt comprising webbing of less tensility than that of said shoulder belt.

4. A seat belt as defined in claim 3, said'belt comprising first warp consisting of yarn of medium strength high tensility and at least second and third warp, said second and third warp being selected from yarn of low strength low tensility, medium strength medium tensility, high strength low tensility as compared with the strength and tensility of said first warp, said first warp constituting a first texture together with weft consisting of yarn of medium strength high tensility, said second and third warp constituting a second texture together with said weft, all said warp being not broken until the initial load applied to the webbing reaches a predetermined value set between 500 1,100 kg, said warp also having comparatively great strength not to elongate in proportion to an increase in the load, second and third warp being broken gradually and repeatedly sustained by the first texture until the tensility attains 1O 20 percent after the initial load reached the predetermined value thereby enabling the webbing to elongate without increasing the load applied thereto, said webbing constituting a multiple-step give member wherein the load-flection curve substantially forms a parallelogram and restoration of the webbing with violent resil- 6. A seat belt as defined in claim 2 wherein the shoulder belt comprises at least two straps passing over the right and left shoulders of the human body respectively.

7. A seat belt as defined in claim 3 wherein the shoulder belt comprises at least two straps over the right and left shoulders of the human body respectively.

8. A seat belt as defined in claim 4 wherein the shoulder belt comprises at least two straps passing over the right and left shoulders of the human body respectively. l l 

1. A seat belt comprising a shoulder belt and a waist belt, said shoulder belt comprising at least in part first warp consisting of yarn of medium strength high tensility and webbing including at least second and third warp, said second and third warp being selected from yarn of low strength low tensility, medium strength medium tensility, high strength low tensility as compared with the strength and tensility of said first warp, said first warp constituting a first texture together with weft consisting of yarn of medium strength and high tensility, said second and third warp constituting a second texture together with said weft, all said warp being adapted not to break until the initial load applied to the webbing reaches a predetermined value between 200 - 800 kg, said warp also having comparatively great strength not to elongate in proportion to an increase in load, second and third warp being gradually and repeatedly broken sustained by the first texture until the tensility attains 20 - 30 percent after the initial load reached the predetermined value thereby enabling the webbing to elongate without increasing the load applied thereto, said webbing being a multiple-step give member having a load-flection curve which is substantially a parallelogram wherein restoration by great resilience is prevented by the correlative action between the first and second textures after removal of the load, said waist belt comprising webbing of less tensility as compared with said shoulder belt.
 2. A seat belt as defined in claim 1 wherein the waist belt comprises first warp consisting of yarn of medium strength high tensility and at least second and third warp, said second and third warp being selected from yarn of low strength low tensility, medium strength medium tensility, high strength low tensility respectively as compared with the strength and tensility of said first warp, said first warp constituting a first texture together with weft consisting of yarn of medium strength high tensility, said second and third warp constituting a second texture together with said weft, all said warp being adapted not to break until the initial load applied to the webbing reaches a predetermined value set between 500 - 1,100 kg, said warp also having comparatively great strength not to elongate in proportion to an increase in load, second and third warp being broken gradually and repeatedly sustained by the first texture until the tensility attains 10 - 20 percent after the initial load reached the predetermined value, thereby enabling the webbing to elongate without increasing the load applied thereto, said webbing constituting a multiple-step give member wherein the load-flection curve substantially forming a parallelogram and restoration with violent resilience is prevented by a correlative action between the first and second textures after removal of the load.
 3. A seat belt comprising a shoulder belt and a waist belt wherein said belt includes at least in part first warp consisting of yarn of medium strength high tensility and at least second and third warp, said second and third warp being selected from yarn of low strength low tensility, medium strength medium tensility, high strength low tensility as compared with the strength and tensility of said first warp, said first warp constituting a first texture together with weft consisting of yarn of medium strength high tensility, said second and third warp constituting a second texture together with said weft, the volume of third warp and the tension of first warp being comparatively increased, a peak load higher than said predetermined value being adapted to work transitionally upon the webbing prior to the initial load reaching the predetermined value set between 200 - 800 kg thereby caUsing said warp to break, said warp being not broken until the load applied to the webbing reaches the value of said peak load, said warp also having comparatively great strength not to elongate in proportion to an increase in the load, second and third warp being broken gradually and repeatedly by a load substantially identical with the value of said predetermined load sustained by the first texture until the tensility attains 20 -30 percent after the initial load reached said predetermined value thereby enabling the webbing to elongate without increasing the load applied thereto, said webbing having multiple-step give with the load-flection curve formed substantially in the shape of a parallelogram wherein restoration with violent resilience of said webbing is prevented by a correlative action between the first and second textures after removal of the load therefrom said waist belt comprising webbing of less tensility than that of said shoulder belt.
 4. A seat belt as defined in claim 3, said belt comprising first warp consisting of yarn of medium strength high tensility and at least second and third warp, said second and third warp being selected from yarn of low strength low tensility, medium strength medium tensility, high strength low tensility as compared with the strength and tensility of said first warp, said first warp constituting a first texture together with weft consisting of yarn of medium strength high tensility, said second and third warp constituting a second texture together with said weft, all said warp being not broken until the initial load applied to the webbing reaches a predetermined value set between 500 - 1,100 kg, said warp also having comparatively great strength not to elongate in proportion to an increase in the load, second and third warp being broken gradually and repeatedly sustained by the first texture until the tensility attains 10 - 20 percent after the initial load reached the predetermined value thereby enabling the webbing to elongate without increasing the load applied thereto, said webbing constituting a multiple-step give member wherein the load-flection curve substantially forms a parallelogram and restoration of the webbing with violent resilience after removal of the load is prevented by a correlative action between the first and second textures.
 5. A seat belt as defined in claim 1 wherein the shoulder belt comprises at least two straps passing over the right and left shoulders of the human body respectively.
 6. A seat belt as defined in claim 2 wherein the shoulder belt comprises at least two straps passing over the right and left shoulders of the human body respectively.
 7. A seat belt as defined in claim 3 wherein the shoulder belt comprises at least two straps over the right and left shoulders of the human body respectively.
 8. A seat belt as defined in claim 4 wherein the shoulder belt comprises at least two straps passing over the right and left shoulders of the human body respectively. 